The present invention relates to an improved caliber bar for determining the longitudinal centerline of the bore at the muzzle end of a gun.
By way of background, after a gun or rifle has been fired a number of times, the bore at the muzzle end of a gun may be distorted so that its centerline no longer coincides with the alignment of the sights associated therewith. In the case of small caliber weapons capable of being carried by a person, several test rounds are fired at a target and the sights are adjusted to coincide with the line of fire. In the case of larger caliber weapons, various mechanical and/or optical devices have been developed for determining the centerline of the bore at the muzzle end of the gun. Some of these devices determine the bore centerline by direct measurement, others use indirect measuring means often determining a line parallel but not coaxial with the gun bore centerline. Devices, such as shown in U.S. Pat. No. 4,459,757, did not determine the centerline with accuracy within a short enough time period to be of use in the field.